Fuse



Dec. 7, 1.948. H..J. NICHOLSv FUSE Filed April 14, 1943 2 Sheets-Sheet 2 Patented Dec. 7, 1948 This invention `relates to base-detonating fuses for armor` piercing.high-egtplosive iprojectiles, such as anti-tank projectiles.-

The invention 3 will i ccordingly .be hereinafter described with relation to such lapplicatiombut it is to be `understood thatwithout material modi- Y fication manyfeatures are eduallyapplicable to other typesiof fuses.A Y'

Detneting fuses l fdr, l.small ,armor Piercing projectiles presentparticulargdiiculties because of the tremendous forces .towhich theyare'subjected in ringnandduring pellctrationofarmor. Theyrmustcontain a relativelylarge detonator capable of producing high-orden detonation (of relatively insensitive explosive shell-lllers,yet at the same time they mustbe, entirely safe in storage, handling and ltiring, and reliablein action on impact. a ,xf' M .3.; Y

In general;n fuses` ofthis'type. are required to be (l) simple in AIdesign andoperation, (2);.easyto v farry James Nichols, lNew York, N. Y.

imputation April v14, 1943, serial No. 483,028

sciaims. (011102479) Fig la shows in transverse Vcross section a View of Fig. l taken at'the plane indicated by a-a in Figi-1;' l

.FigI-Z shows the same fuse in the same section as in Fig.` 1, the mechanism being shown in ring position,fthat is, While in the bore of the gun while being red therefrom;

Fig. 2d shows the fuse of Fig. 2 in transverse crosssection at the plane indicated by Zeb-2c;

Fig.'.3' shows the same fuse in the same section .as in Fig. 2, but with the mechanism in the position of night after ring; Y

Fig. Bashows the same fuse as in Fig. 3 in transverse cross section at the plane indicated by a-ain Fig. 3;

Fig- 4 is another longitudinal cross section of the same fuse, the mechanism being shown in manufacture and load, 5(3) .free from deterioration in storagefl) safe in handling and storage, and (5) certainin action.; .a i.

In particular,the fuse of theinvention meets these requirements and `provides "thexadditional features` of short delay action.. on A:substantially normal impact, and grazeiaction, on striking a target at highly lobliquenangles where a percussion fuse ofr conventional 'design Wouldfail toiact throughlack of sufdcientiaxial.retardation in relation to the transverse force of impact; The

fuse is 'also adaptedto A:carryiatracer in the base. The ring mechanism is detonator-safe, bore-safe, `and muzzle-safemf f These features in combination make -the'fuse ofthe `invention particularly rusefulforlattacking i tanks `and their accompanying forceaar'mored cars and trains,` 1pill.boxes,and other armored or protected targetsw "N: f VI i 15 It is f therefore one" bfi' the principalcbjects iof this inventioni to :meet the `general i and Athe "partcular .requirements and "to"l embody "the novel features above stated in a highlyeflicient reliable and practicalmanner.r i i Other objects will`=bef parti; obvious andin parthereinafter'indicatedin the description of thisembodimentpf the invennc.- U n Inl-the i drawing f`.nr`r`1`in'gtpalrtfof` this disclosure eine ins'tratinggone of various "possible embodiments; likel charactersfjof reference denote corresponding parts t ghott `the 's'everalviewsnin Fig. 1 showsin'yenlarged :longitudinal cross 4sectiona base Vpfercussir detnating `fuse accordingtotneinventicn; ecnamjsm'beinglsnown inunarmed'or'safe position;

exploding position as a result of substantially normal impact with a target; Fig. 4a. is a section on line D-D of Fig. 4;

Fig.' 5 is a further longitudinal section of the same fuse, the mechanism being shown in exploding position as the result of highly oblique or graze impact with a target; and

Fig. 5u is a section on line E-E of Fig. 5.Y

Referring now to these drawings and especially to Figs. 1` and 1a, the main structural member of thegfruse is -the body I0 of relative massive proportions and preferably `of impact resisting alloy steel, with strong external screw threads II for assembly to the base of the projectile (not shown) The body is preferably bored out at the rear with respect to the base of the projectile to provide a blind cavity l2 in which a .pyrotechnc tracer is adapted to be loadedralthough this feature can be omitted without detriment to the fuse mech# anism. The body Ill isalso bored outfrom the front, or inner end to provide an internal blind bore I3 in which the ring mechanism is as'- sembled. The bore I3 is slightly recessed at the bottom for a purpose tobe described later, and the front'fportion of the bore is threaded at I4 to provide a-stiong connection for the rotor housing, I5 whichj is screwed therein. This housing I5 `is bored out Afrom the inner .end almost to the-outer end to provide a vblind cavity l' with a` spherical `seat l1 adapted to bear a round rotor I IlA of the vgeneral type disclosed in my applicaticn Seria1.No. 303,294, iiled November 7, 1939, nowgPatent No. 2.446.019. It islalso counterbored tofprovide a shoulder 2i! to support a primer holder 2|, and a cavity 22 to receive an inertiapercussion plunger 23. Rearwardlyof the percussion plungerk 23 is mounted in alspecial manner a graze disc 24. 1. The l rotor I8, of general centro-symmetric round form, has a diametral bore containing a detonator 25, preferably enclosed in a metallic capsule 26, and two similar torque increasing grooves or channels 21 extending on opposite sides of and parallel to the detonator bore. The rotor i8 is normally retained in unarmed position in which position the axis of the detonator 25 lies obliquely to the axis of the fuse and is therefore ineffective to produce detonation. The rotor I8 is held in unarmed position by four detents 28 working in diametral cross holes 30,

the longer two of which extend into the torque' l to be noted that the arming takes place in two increasing channels 21 to provide loose pivotsm,

for the rotor, and the shorter two into shallow recesses 29 at right angles, Fig. la., located di ametrally opposite on the equator of the rotor i8. The detents 28 are elastically held in position of engagement with the rotor by a' circlet spring 3| mounted in an annular groove in the rotor housing.

"The primer holder 2| mounts a primer 32 'in the axis of the fuse, and is retained in position onshoulder 26 by ay retainer ring 33 partly recessed in` a groove 34. A firing pin 35 having aiiring point'on its Vforward endis a slide fit in an axial hole 36 in plunger 23, except for the over-size knurled portion 31, which upon being forced partly in plunger 33 provides a connection therewith of predetermined strength. The conical rear end 38 of firing pin 35 seats in a conical recess 40 in graze disc 24 to maintain that disc in concentric relation to the axis of the fuse. Shallow recess 4I in the bottom of bore i3, as priorly mentioned, also aids in keeping the grazedisc 24 concentric. The plunger '23 has a similar `conical rear end to t the` cone 4l) and is provided with a pair of grooves in which are seated expansion rings 42 respectively which act jointly as an anticreep device and also hold the plunger 23 firmly in the armed position during flight, preventing side-wise movement of graze disc 24 until impact.

Referring to thedrawings in sequence, the operation is as follows:

In Fig. l, which shows the mechanism in assembled position, which is also the safe, unarmed position, it is to be'noted that the plunger 23 masks `the viiring-point of pin 35 from primer 32; and firing pin 35 holds the graze disc 24 centered; and the detents 28 retain the rotor I8 in unarmed position.

In Fig. 2, which shows the relative position of the parts of the mechanism during firing from a gun, all parts tend strongly to move towards the rear due to their inertia while the projectile is being accelerated, this tendency being known as set-back. The plunger 23 is drivelf'rearwardlyby set-back, unmasking the firing point 35 and seating itself in the conical seat in the graze disc 24. Simultaneously, crclet spring 3l slips backwardly as shown due to setback, releasing detents' 28. But due to set-back, detents 28 and rotor I8 are immobilized and cannot respond to any centrifugal force acting while the projectile is in thebore of the gun.

In the event the primer or the detonator should be set off by the force of concussion of ring, the detonator would explode harmlessly. And should the projectile encounter coppering or any other obstacle in the bore of the gun capable of momentarily reversing the acceleration of the projectile, the rotor I8 would be unable to arm the detonator while the projectile remained in the bore of theA gun. Hence, it is evident that the invention provides adequate safe guards against premature explosion of the detonator,

stages, namely, the arming of the firing pin and the removal of the restraint of the Circlet spring 3| on the detents due to set-back in the gun; and the lateral movement of the detents and the turning of the rotor to arm the detonator responsively to centrifugal force after the projectile leaves the muzzle. of the gun. This latter stage in the arming is not complete until the projectile is fty feet or more'beyond the muzzle of the gun, hence it is evident that the firing mechanism of the invention is muzzle-safe as well asdetonatorsafe and bore-safe.

Referring to Iig.- 4, on striking a target the projectile will ybesuddenly checkedin ight and the percussion lplunger 23 will continue onward due to its inertia, thus plunging relatively forward and thereby striking the iiring point against the primer l32, exploding same. The primer will after a very short delay ignite the detonator 25 which will' instantly explode, breaking through the thin diaphragm 43 of the concentrator hole 44, thereby delivering an exploding blow to the explosive shell-filler (not shown) which fragments the projectile. .It is to be noted that the intensification of the detonator force by the concentrator hole 44 enables the detonator to explode the shell-filler directly,thus eliminating the need for a booster charge which has heretofore been considered essential for fuses of this class. Thislnovel feature of the invention enables the fuse to be made smallerand simpler, saves the cost of thek booster explosive and the loading thereof, :provides more room in small projectiles for shell-filler, and generally adds to the efficiency of the fuse as a whole.

It is also lto be noticed-that 'should the threads holding rotorhousing l5 in body l0 be stripped due to the force of impact, the housing will hold the exploding 'mechanism intact, thereby enabling the fuse to function as designed despite such structural failure.

Referring now to Fig. 5, which shows the graze-action of Itlieifuse, on striking a target ata highlyoblique angleor on glancing from the ground, the projectileis exploded in the manner just described, except that the primary cause is not the forward thrust of the percussion plunger on striking the target, but is rather the transverse movement ,of. the graze disc 24 due toits inertia relative to cross-forces resulting from; theimpact. 'j The origin and manner of acting of cross-forces on oblique impact of projectiles with armoris described in detail in my U. AS. 'Patent No.- 1,656,361, `-dated January 17,

1928. For present, purposes; it need-only be considered that-on-oblique impact with armor the v crossforce may exceed theaxial retarding force,

whereupon the usual, percussion plunger will fail to act. But undersuch circumstances, the graze disc will be driven'for'c'ibly side-ways, and the conical, concave surface thereof will wedge the percussion plunger forwardly as shown, exploding the primerand 'starting the detonating train priorly'described.` 'Ijlusthe graze disc improves the performance of the fuse on oblique impact with armor and other targets, while the short delay burst increases the destructiveness of projectile against the target in well understood As a further example ofthe advantages provided by the invention, it may -be cited that when a projectile fired at a tank misses its target, which happens in the great majority of cases, solid shot or conventionally fused projectiles usually glance oif the ground back of the target and land in the rear beyond the theater of action without military result. But with the fuse of the invention, such misses will explode immediately after glancing from the ground, producing the effect of high-explosive shrapnel. Such graze action bursts are known to be highly effective against unsheltered troops, as for example the tank accompanying troops in desert warfare. Thus by means of the fuse of the invention, armor piercing anti-tank projectiles are made more efcient against other incidental targets, and their military value is enhanced.

To summarize, the novel fuse of the invention provides a burstafter a short delay back of armor plate encountered at normal and oblique angles, and on glancing impact with the ground or other obstruction an air burst after a short delay, simulating shrapnel fire. These fuse characteristics enhance the military value of antitank projectiles, particularly with respect to their effectiveness against incidental troops. These advanced features are obtained with a safe, simple, reliable, and rugged mechanism, able to withstand the most severe impacts.

Without further analysis, it should be evident from the foregoing that the invention provides novel and advantageous features in fuses, and that the invention as a whole, while simple in form, meets the complex general and special requirements for fuses of this class in a highly efficient and practical manner.

I claim:

1. In a base detonatng fuse for explosive armor-piercing projectiles for riiied guns, in combination, a cylindrical fuse Vbody having an axial bore; and detonatng mechanisml therein comprising a substantially spherical centrifugally armed rotor mounted on the axis of the fuse at the forward end of said body, a detonator carried by said rotor in normal safe position, means for retaining said rotor in unarmed position, a percussion plunger carryinga firing pin and mounted axially slidable, a holder carrying a primer for igniting said detonator mounted between said rotor and said plunger, and transversely movable means mounted rearwardly of said plunger and having a wedging relation thereto for forcing said firing pin into exploding relation to said primer upon oblique impact with a target.

2. In a base detonatng fuse of the class described, in combination, a cylindrical fuse body having an axial bore, and detonatng mechanism therein comprising a substantially spherical centrifugally armed rotor mounted on the axis of the fuse at the forward end thereof and carrying a cylindrical detonator in normal safe position, said rotor having a pair of channels for increasing the centrifugal torque thereof, a holder carrying a primer for igniting said -detonator mounted rearwardly of said rotor, and a percussion element mounted for axial movement relative to said holder and carrying a firing pin adapted to explode said primer on substantially normal lmpact with a target.

3. In a base detonatng fuse of the class described, in combination, a cylindrical body having an axial bore and detonatng mechanism therein including a centrifugally actuated rotor carrying a cylindrical detonator mounted diametrically therein, means for normally holding said rotor in unarmed position but removable by centrifugal force, and means for exploding said detonator including a percussion plunger and a firing pin, said plunger being adapted to slide longitudinally on said firing pin at set-back to arm said firing pin, said rotor being characterized by having a pair o-f channels for increasing the centrifugal torque thereof.

4. In a fuse for rotative projectiles, in combination, a substantially cylindrical body adapted for assembly with such projectiles and having an axially concentric bore, a housing structure assembled in said bore carrying a symmetrical rotor carrying a cylindrical detonator in safe position and mounted for rotation in said housing when released, said rotor being adapted to turn said detonator to armed position responsively to centrifugal force, means for normallyy retaining said rotor in unarmed position and for releasing same for rotation when said fuse is red in a projectile; and firing means for said detonator when in armed position, including a cylindrical percussion element slidably assembled in said structure and having a coaxially extending firing pin, and an inertia element mounted for transverse movement in said body and adapted to wedge said percussion element axially towards said detonator upon oblique impact of said projectile.

5. In a base detonatng fuse for rotative antitank projectiles, in combination, a hollow cylindrical fuse body adapted for assembly with such projectiles, and percussion iiring mechanism therein characterized by multiple safety means and by being particularly adapted to provide reliable exploding action upon oblique impact with armor or grazing impact with the ground comprising a detonator, a symmetrical centrifugally actuated safety rotor carryinglsaid detonator, safety means for normally retaining said rotor in safe position and for releasing it for rotation when the fuse is red in a gun, safety firing means for said detonator including a percussion element having an axial bore with a normally masked firing pin therein, and oblique impact firing means including a transverse inertia element adapted to wedge said percussion element axially to cause firing of said detonator upon impact with a target or incidental obstruction at a greater angle of obliquity than will normally actuate said percussion element.

HARRY JAMES NICHOLS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 697,974 Broderick Apr. 22, 1902 815,958 Harriman Mar. 27, 1906 k823,681 Gulick June 19, 1906 1,356,633 Kirchhoff Oct. 26, 1920 1,473,355 Pillars Nov. 6, 1923 1,534,011 Watson Apr. 14, 1925 2,155,100 -Scelzo Apr. 18, 1939 FOREIGN PATENTS Number Country Date 837,467 France Nov. 12, 1938 

